The present invention generally relates to electric motors or generators. More particularly, the present invention relates to electric motors having a brush assembly used to create an electrical connection between a power supply and a commutator. Most particularly, the present invention relates to a motor-fan unit having an end plate and a diffuser that when assembled secure the brush assembly in operative relation with the commutator.
Electronic motors and generators are well known in the art and have been put to use in a variety of applications. One application is the handling of air. In these circumstances an electric motor is coupled with a fan to create a flow or vacuum as necessary. Often, the fan is used to provide cooling air to the motor. In these instances, a fan mounted on a shaft driven by the motor draws air into a fan shroud to compress or pressurize the air. The pressurized air is released into the motor housing via one or more ports which direct the air across the motor windings to draw heat into the flow and exhaust it from the motor housing.
The motor includes several components including field windings, that surround a centrally located shaft, which is rotatably mounted in suitable bearings. A commutator is mounted on the shaft and placed in electrical contact with a power supply by a pair of opposed brushes contacting the commutator. In most motors found in the industry, the motor""s components are supported on a skeletal frame, which is often made of metal to provide adequate support. Recently, non-metal molded motor frames and housings have been used to reduce the weight of the motor and reduce the leakage prevalent in skeletal designs. In either case, the commutator brushes must be supported by the motor frame. In skeletal frames, a shelf is provided adjacent the commutator with the brush supported thereon. A U-shaped clip is placed over the brush and fastened to the shelf, by screws, to secure the brush next to the commutator. In the non-metal frames, tube-like fittings are provided to support the brushes. These fittings add complexity to the molding of the motor components and often require the use of mandrels or sacrificial molding techniques. While it is desirable to use molded products in the construction of motor-fan assemblies to reduce leakage and improve efficiency, the additional complexity of molding the brush fittings reduces the ability of such devices to remain cost effective. Additionally, these fittings are closed off from the cooling air stream reducing the heat transfer rate at the brushes. The reduced heat transfer at the brushes, thus, reduces the efficiency of the motor. Therefore, there is a need for a motor-fan unit that addresses at least one of these deficiencies in the art.
It is, therefore, an object of the present invention to provide a motor-fan unit employing a more simply molded brush retainer. It is another object of the present invention to provide a brush retainer that is formed such that it is open in the axial direction.
Another object of the present invention is to provide a motor-fan unit having a brush retainer that is in fluid communication with the air flow generated by the fan, such that the brush receives cooling air therefrom.
In view of at least one of these objects, the present invention generally provides a motor-fan unit including a motor assembly having a shaft, a commutator supported on the shaft, and a pair of brushes in an electrical contact with the commutator, a fan assembly having an impeller coupled to the shaft, an end plate assembly located between the impeller and the motor assembly, said end plate assembly including a plate portion defining an opening throughwhich the shaft passes, wherein said commutator is located near the opening, and a pair of brush retainers adapted to receive the brushes formed on the plate portion adjacent said commutator, the brush retainers opening toward the fan assembly.
The present invention further provides an end plate assembly in a motor-fan unit including a plate portion and a bracket portion adapted to be attached to the motor, the plate portion having a commutator receiver formed thereon, the commutator receiver defining a well that at least partially receives the commutator.
The present invention further provides a diffuser in a motor-fan unit including a plurality of channeling members spaced about a central bore, and a pair of brush cap projections extending axially motor in toward the motor-fan unit.
The present invention further provides a combination diffuser assembly and end plate assembly in a motor-fan unit including an end plate assembly having a plate portion, a pair of brush retainers extending axially toward the motor from the plate portion defining a mouth that opens toward the diffuser assembly, a pair of projections formed on the diffuser assembly corresponding to the brush retainers and at least partially extending into the mouth.